Load-handling vehicles, including forklift trucks, piggyback forklift trucks and other similar type vehicles are commonly used throughout the world. These vehicles are generally used for the movement of goods in a factory or for the movement of materials about a site. Typically, these vehicles are provided with a driver's station, otherwise referred to as a driver's cab, which is positioned either centrally or to one side of the load-handling vehicle. These drivers' cabs typically comprise a roll cage having a plurality of uprights bridged at their upper ends by a roof structure which acts as a safety compartment for the driver of the vehicle. The drivers cab further comprises a door to prevent the driver of the vehicle from inadvertently falling from the vehicle when the vehicle is in operation. This is particularly necessary when the vehicle is being operated on uneven terrain such as on a building site or agricultural premises or when the vehicle is travelling at relatively high speeds when turning in a factory environment.
There are however problems associated with the known types of doors. Generally, these doors are mounted to the cab by way of hinges along one side of the door. Therefore, the door must swing outwardly away from the driver's cab when it is opened in order to allow access to and from the cab. When the door is in a fully open position, the door typically protrudes outwards from the drivers station to such an extent that there is a danger that personnel or other machinery could come into contact with the open door.
This often results in either significant damage to the door or the machinery and in certain situations this may result in injury to the personnel even when the vehicle is stationary. It has been known in the past for such load-handling vehicles to be operated with the door in an open position, either deliberately or accidentally, which has resulted in serious injury to individuals and machinery impacted by the open door.
One such door that is mounted onto an upright in this manner is described in U.S. Pat. No. 6,890,036. This patent describes a drivers cab having a door mounted onto a rear upright by way of a pair of hinges. The door is secured in a closed position by way of a locking bolt on the door which mates with a complimentary locking member on a front upright. An actuating element for releasing the locking bolt is mounted on top of the door. Another similar type of drivers cab is described in European Patent Application Publication No. EP 0992382 where there is shown a door that is pivotally connected to a rear upright by way of a hinge and is secured in place to a forward upright by way of a lock system. In order to gain access to or from either of these cabs, it is necessary to swing the door outwardly away from the vehicle about the hinge joints.
Another problem with the known types of door generally is that the doors, by their very nature, have a tendency to swing outwardly when a significant force is exerted on the door from within the driver's cab. It has been known for these doors to inadvertently open as a result of the driver being thrown against the door in the event of a high speed turn or an accident. Often, the driver's weight alone impacting against the door will be sufficient to cause the door to open and in other circumstances the driver will accidentally disengage the locking mechanism on the door as he or she is thrown against the door. It is at these times when the door is most needed that it is most likely to fail. Opening of the door in these circumstances has been known to result in serious injury to the drivers of the vehicle. This has resulted in the requirement for more and more elaborate and expensive locking mechanisms being provided with these doors. Typically, at least a portion of these elaborate locking mechanisms is mounted on an upright opposite the upright about which the door is mounted thereby requiring additional assembly which substantially increases the cost and complexity of manufacture of the vehicles.
One drivers cab for a load handling vehicle that does not describe a door that must pivot outwardly away from the vehicle in this manner is described in U.S. Pat. No. 4,392,660. This patent describes a safety bar that pivots upwardly across an opening in a drivers cab to prevent a driver from falling from the cab. This device describes a vertical member which is pivotally connected to hinge plates secured to the floor of a vehicle, and a horizontal member which is secured to the vertical member that blocks the opening. The horizontal member has a locking portion for reception in a latch bar on a forward upright in the drivers cab. Although this door will not pivot outwards when being opened, it requires a significant amount of space to be mounted on a vehicle and is only practical on the largest earthmoving machines and the like. This door would not be practical in smaller load-handling vehicles and in particular piggyback forklifts where space is at an absolute premium. A further disadvantage of this type of door is that it also requires a complimentary locking mechanism provided on an upright that entails additional manufacturing expense and complexity.
It is an object therefore of the present invention to provide a door for a load-handling vehicle that overcomes at least some of the above-identified problems that is both simple and cost efficient to manufacture. It is a further object of the present invention to provide a door for a load-handling vehicle that does not protrude away from the driver's cab by a significant distance and that is not prone to inadvertent opening on impact from within the driver's cab.